Sigh HD probs

Question

So my HDD has a small issue with it, nothing that impacts performance or usability, so the S.M.A.R.T. status is failing, Can't get to the partition tab to format it for GUID, and I can't install 10.10 without it... I got away with it on 10.9 but meh, and every time I try to format for GUID under windows, 10.10 installer doesn't wanna touch it cause it's some windows reserved partition, any advie on how I can format GUID for Mac OSX under windows?